## ‘Goodnight’ Kepler

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One of the most popular mission of NASA, Kepler Space telescope has come to an end!

Kepler is named after the German Astronomer and Mathematician, Johannes Kepler. In the seventeenth century, Johannes Kepler put forward his laws of planetary motion. These are three laws describing the movement of a planet around the Sun.

## THE ‘GOODNIGHT’

NASA launched Kepler on March 7, 2009.

On the evening of November 15 (2018), NASA’s Kepler space telescope received its final set of commands to disconnect communications with Earth.

The “goodnight” commands finalize the spacecraft’s transition into retirement, which began on Oct. 30 with NASA’s announcement that Kepler had run out of fuel.

It is coincidence that Kepler’s ‘goodnight’ was on the death anniversary of Johannes Kepler exactly after 388 years of Johannes Kepler’s death!

The spacecraft is now drifting in a safe orbit around the Sun 94 million miles away from Earth.

The data Kepler collected over the course of more than nine years in operation will be mined for exciting discoveries for many years to come.

### GOAL

NASA started the mission to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in the habitable zone, and determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets.

The mission also aimed to—

• Determine the percentage of terrestrial and larger planets that are in or near the habitable zone of a wide variety of stars
• Determine the distribution of sizes and shapes of the orbits of these planets
• Estimate how many planets there are in multiple-star systems
• Determine the variety of orbit sizes and planet reflectivities, sizes, masses and densities of short-period giant planets
• Identify additional members of each discovered planetary system using other techniques
• Determine the properties of those stars that harbor planetary systems.

### TRANSIT METHOD OF DETECTING PLANETS

When a planet crosses in front of its star as viewed by an observer, the event is called a ‘transit‘.

Planets block some light of the star according to its size, when the planet passes in front of the star, and this changes the brightness of the star.

Kepler used this method to detect different star systems and planets in the galaxy.

## REFERENCES

1. Chen, Rick. Kepler Space Telescope Bid ‘Goodnight’ With Final Set of Commands | NASA. Last Updated November 16, 2018. https://www.nasa.gov/feature/ames/kepler-space-telescope-bid-goodnight-with-final-set-of-commands (accessed November 17, 2018).
2. Johnson, Michele, and Brian Dunbar. Mission overview | NASA. Last Updated October 31, 2018. https://www.nasa.gov/mission_pages/kepler/overview/index.html (accessed November 17, 2018).

## Dawn comes to Dusk

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NASA’s Dawn spacecraft was a mission to study the two most massive bodies in the asteroid belt (between Jupiter and Mars) — VESTA and CERES. It was launched in 2007 and ended its journey on November 1, 2018.

Ceres is a dwarf planet like PLUTO, which was supposed to be a planet at a time. Ceres is the only dwarf planet in the INNER SOLAR SYSTEM.

Vesta is a rocky asteroid.

When Dawn visited Vesta and Ceres, it made us realize that these both evolved very differently from each other and faced a number of processes in their evolution.

Dawn orbited (and explored) Vesta in 2011-2012 and it is in orbit around Ceres since March of 2015.

Dawn delved into the unknown worlds and increased our knowledge of the development of the two bodies.

It is the first mission to orbit an object in the main asteroid belt, the first to visit a dwarf planet, and the first to orbit two deep-space destinations.

## MAJOR DISCOVERIES BY DAWN

Dawn orbited Vesta for more than an year and found unexpected carbon rich material on its surface which scientists hadn’t observed before.

When it started orbiting Dwarf Ceres, it found something more unexpected — An ocean world of Water and Ammonia.

Dawn even found some organic matter on the surface of Ceres.

## THE ‘DUSK’

On November 1, 2018, Dawn ended its mission and will remain around Ceres for some further decades. Actually, the spacecraft has gone silent.

The reason for the end of this historic mission is that Dawn has ran out of HYDRAZINE, the fuel of Dawn. So, Dawn can no longer turn its solar panels to be recharged by the Sun.

“Today, we celebrate the end of our Dawn mission – its incredible technical achievements, the vital science it gave us, and the entire team who enabled the spacecraft to make these discoveries,”

— said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington.

He continued,

“The astounding images and data that Dawn collected from Vesta and Ceres are critical to understanding the history and evolution of our solar system.”

“The fact that my car’s license plate frame proclaims, ‘My other vehicle is in the main asteroid belt,’ shows how much pride I take in Dawn,”

— said Mission Director and Chief Engineer Marc Rayman at NASA’s Jet Propulsion Laboratory (JPL).

“The demands we put on Dawn were tremendous, but it met the challenge every time. It’s hard to say goodbye to this amazing spaceship, but it’s time.”

“In many ways, Dawn’s legacy is just beginning,”

— said Principal Investigator Carol Raymond at JPL.

“Dawn’s data sets will be deeply mined by scientists working on how planets grow and differentiate, and when and where life could have formed in our solar system. Ceres and Vesta are important to the study of distant planetary systems, too, as they provide a glimpse of the conditions that may exist around young stars.”

Dawn will remain in orbit for at least 20 years, and engineers have more than 99 percent confidence the orbit will last for at least 50 years.

## References

1. NASA. NASA’s Dawn Mission to Asteroid Belt Comes to End. November 01, 2018. https://www.nasa.gov/press-release/nasa-s-dawn-mission-to-asteroid-belt-comes-to-end (accessed November 04, 2018).
2. NASA. Dawn Mission | Mission. https://dawn.jpl.nasa.gov/mission/ (accessed November 04, 2018).